Electrical condenser



Sept. 22, 1931. w P s 1,824,569

ELECTRICAL CONDENSER Original Filed Jan. 6, 1922 5 Sheets-Sheet l avwemtoz Sept. 22, 1931. w. H. PRIESS ELECTRICAL CONDENSER 5 Sheets-Sheet 2 Original Filed Jan. 6 1922 m m 0 n w W 5 Sheets-Sheet 3 P 1931- w. H. PRIE SS ELECTRICAL CONDENSER Original Filed Jan. 6, 1922 x4 aw 3 C 4 u i V/I VII /II I. In I [ll dab/r11? s8 A TTORNE Y P 1931- w. H. PRIESS 1,824,569

ELECTRICAL CONDENSER Original Fil ed Jan. 6. 1922 s Sheets-Sheet 4 Sept. 22, 1931. w. H PRIESS ELECTRICAL CONDENSER Original Filed Jan. 6. 1922 5 Sheets-Sheet 5 A TTORNE Y Patented Sept. 22, 1931 UNITED STATES PATENT- OFFICE WILLIAM H. PBIESS, OF UPPER IONTCLAIB, NEW JERSEY, ASSIGNOB TO WIRELESS SPECIALTY APPARATUS COMPANY, 01' BOSTON, MASSACHUSETTS, A CORPORATION 01' NEW YORK mBICAL CONDENSER Application filed January 8, 1988, Serial 110. 587,449. Renewed Icbruary 18, 1981.

This invention relates to electrical condensers.

The condensers of the present invention, of which several forms are illustrated and I described, are of eneral application or use. By way of exampiia, they are adapted for use as series antenna condensers, grid condensers, key condensers, bypass condensers, dummy circuit condensers and receiving circuit condensers, for amateur or commercial use in radio communication.

The condenser of this invention com rises a stack composed of alternate sheets 0 conductors and dielectric, the conductors comprising foil preferably of lead, tin or copper, and the dielectric being preferably of mica, with the sheets of foil and dielectric in intimate contact, or substantially so, and preferably treated with wax or some other 2 insulating material.

An object of the invention is to'provide a low cost, compact condenser of high eflicie'ncy.

Another object of the inventionjs to provide an improved clamp for the stack. Another object of the invention is to provide clamping means which exerts a spring pressure on the stack to maintain the elements or sheets thereofin intimate contact.

Another object of the invention is to pro vide improved means for securing and protecting the terminal leads.

Another object of the invention is to provide a construction of series section stack in which the leads may be brought out at opposite ends, irrespective of the number of sections.

Another object of the invention is to provide an improved casing for the condenser Stack.

In the accompanying drawings, I have illustrated embodiments of the invention in which Figure 1 is an elevation of one embodiment in an assembled condenser;

Fig. 2 is a bottom planview thereof;

Fig. 3 is an end view thereof looking in the direction of the arrow, Fig. 2;

Fig. 4 is a perspective view of one of the casing or clamping parts; to Fig. 5 is a perspective view of the other casing or clamping part, the broken lines indicating the untensioned or unstressed condition of this part prior to assembly;

Figs. 6 and 7 are perspective views of insulatlng parts used in the construction of the above condenser;

Fig. 8 is a diagrammatic expanded view of a condenser stack, illustratin a method of assembling the sheets of die ectric and foil and their connections;

Fig. 8a is a diagrammatic ex anded view of another arrangement of condbnser stack;

Fig. 9 is a diagrammatic plan view of the construction of Fig. 8;

Fig. 10 is a sectional plan view of one end of the above condenser of Figs. 1-7 on the line 1010 of Fig. 1, illustrating the method of attaching the leads and embedding the same;

Fig. 11 is a diagrammatic illustration of a series section stack having an even number of sections, showing how the leads come out therein at the same end;

Fig.12 is a plan view, with parts broken away, of another form of condenser embody- 7 ing the present invention;

Fig. 13 is an elevation thereof looking at one end, parts being broken away;

Fig. 14 is an elevation thereof looking at the opposite end;

Fig. 15 is a sectional elevation thereof on the line 1515 of Fig. 12, looking in the direction of the arrows;

Fig. 16 is a perspective view on a reduced scale of the casing parts of the construction of Figs. 12 and 19;

Fig. 17 is a perspective view on a reduced scale of the clamp parts of the construction of Figs. 12 and 19;

Fig. 18 is an edge view on a reduced scale of one of the clamping parts of the condenser of Figs. 12-17.

Fig. 19 is a plan view of a third and slightly modified form of condenser, illustrating a less number of leads than the forni of Fig. 12; and v Fig. 20 is an elevation thereof.

In the type of condenser herein illustrated and described, for example, as illustrated in F gs. 19 and 20, in which thestack must be m I as composed of sections or condensers connected in series in certain designs of a given potential and capacity, I found it diflici lt, using the type of series section stack now in use, to

bring the terminal leads out from the stack at opposite ends unless the stack comprised an odd number of sections connected together alternately at opposite ends, as, for instance, as illustrated in Fig. 15. Where the stack comprises an even number of sections connccted in the usual manner as illustrated in Fig. 11, it should be noted that the leads must'be brought out at the same endof the stack. In Figs. 8, 8a and 9,1 have illustrated diagrammatically, the views being expanded, how I am able to bring the leads from opposite ends where an even number of sections or condensers are connected in series. Referring to Fig. 8, I have illustrated a stack comprising one section I) which. for purposes of convenieuce, I will designate as a double section to tion of the type of condenser section now well known and as illustrated in Fig. 15.

Referring to Fig. 8a, the stack compr ses several sections A, B, C connected in series, these sections be' of the proper number. size and area for t e required capacity and voltage. Ashere illustrated, the intermediate section B, a double section like section D, Fig.8, comprises in efiect two condensers connected in series and having integral connec tions with each other, certain of the foil or armature plates of the section forming integi'al series connections between the two condensers of the double section. For this purpose, I have provided a number of flat sheets of dielectric 1 (referring to section I), Fig. 8.. by way of example) on one sideof each of which is a single pair of flat foils 2 spaced from each other at 3 and projecting beyond opposite ends of the dielectric. Upon the opposite side of each dielectric 1 18 a single flat sheet of foil 4 which is arranged as shown in Fig. 9 centrally of the sheet of dielectric, being spacedinwardly from all edges thereof, the pairs of foils 2 alternating with foils 4 with dielectric sheets between them. The foils 4 form common opposing armatures for the pairs of separated foils 2, forming in effect two'condensers connected in series. That is to say, there is a foil 4 between two adjacent sheets of dielectric and pairs of separated foils 2 upon the opposite surfaces of said adjacent dielectrics, the foil 4 constituting a common opposing armature or condenser element for the opposing pairs of foil 2 and also serving as a series connection between the condensers formed by the foils 2 and 4. Figs. 8 and it is to be understood, show expanded views of the stacks, and in actual construction the thickness of the stack would be such as to in the casing illustrated for es:- ample Fig. 29, the sheets of foil and di h it from the single sec-- viding two condensers in effect,

electric being compressed into close contact with each other.

In finishing the double section after its assembly, the projecting portions of the foils 2 at each end are connected together and soldered as illustrated diagrammatically in Figs. 8- and 8a, forming foil terminals 5.

at 6 and 7 in series with a double section 1?, the connections being alternately at oppos te ends of the stack and the single sections being located on opposite sides of the double section. Terminal leads 8 and 9 are thus brought out from or secured to the free ends of sections A and C at opposite ends of the stack. In like manner, terminal leads 10 and 11 are secured to the foil terminals of the stack illustrated in Fig. 8 and proect out at opposite ends. Interposed between the sections A, C and sectional separators 13, preferabl of some cheap insulating material such as lish paper or mica, which, when the condenser stack is assembledjind soldered, Willproject beyond these sections and beyond the connections as illustrated more clearly in Figs. 3 and 10.

The terminal leads, such as leads 8 and 9 or 10 and 11, as illustrated in thedrawings,

comprise preferably stranded copper wire,

that is, a composite lead made up of very small Wires'stranded together and which are B, Fig..8a, are

flared'out at the end which is to be connected f to a condenser foil terminal or a section con nection and is soldered thereto, providing a multi-point attachment, that 7 ment n which a number of very small flexible wires are soldered to the projecting foil term nals or connections. This construction provides a very strong and permanent electr cal connection between the leads and the foil terminals or connections and allows a greater degree of flexibility and relative movement without danger. of stripping the leads or tearing the fragile foil terminals to which they are attached or otherwise damaging the electrical contact therewith.

Cover slips 13a of suitable insulating material may also be placed on opposite sides of the stacks as illustrated in Fig. 8. The construction illustrated in Fig.

series, 2110 theleads 1c and 11 to be brought out at opposite ends. The construction illus-' trated in Fig. 8a, while providing in efl'ect is, an attach- 8, while proconnected in four condensers connected in series, also allows the-leads to be brought out at opposite ends. Where the number of condensers or sections connected in series required is an odd number, single sections may be, although not necessarily, used. In any embodiment of the invention for.even numbers of sections or condensers connected in series, either an odd number of double sections may be used, as for instance illustrated in Fig. 8a, or an odd number of double sections with an even number of single sections, as for eX- ample illustrated in Fig. 8a, according to the number of sections and as convenient, to bring the leads out at opposite ends of the stack. For a sack having six condensers or sections in series, for example, three double.

sections or one double section and four single sections could be connected in series to bring the leads out at opposite ends. For a stack having eight sections or condensers connected in series, three double sections and two single sections may be used, or one double section and six single sections for the purpose of bringing the leads out at opposite ends.

The form of stack or section illustrated in Figs. 8 and 8a at B and D, besides being capable of use for bringing the leads out at opposite ends and thereby lessening the insulation difiiculties, obviates the necessity of soldering the sections together and providing a space for this soldering, the connections in this case being integral with their connected foil armatures and no sectional separator such as illustrated in Fig. 11, being necessary. The double section type herein disclosed has I greater tab or foil terminal strength, where the foils 2 are connected together at 5 and to which the leads and 11 are connected, than a two-sectional form as illustrated in Fig. 11, because, for a stack of the same capacity and number of dielectrics, a

larger number of foils 2 are employed in the former which are connected together.

The path of the current through the sec-- tions or stacks B or D is through one group of short foils 2-, through the dielectrics 1 to the long or floating foils 4, along the foils 4 through the dielectrics again to the second grou of foils 2; that is, the current traverses the ielectrics twice in going from one terminal to the other.

The condenser stacks or sections such as illustrated diagrammatically in Figs. 8 and 8a or such as illustrated, for instance, in Fig. 15 are built up preferably by stacking the foils, dielectric and separators in their proper order, preferably previously dipping the dielectric, which is preferably of m1ca, in melted or li uid insulating material such as y building the stack in such melted or liquid insulating material. The stack or section is then placed in a pressing stand and heated in a bath of molten paraflin at a temperature of approximately 150 C. for about twenty minutes, removed from the bath and cooled under a pressure of the order of 600 pounds. The section or stack should then be tested for breakdown and measured for capacity. The leads should then be soldered to the stack-in their proper place and the sections connected together, and the separators inserted if the stack is to comprise a plurality of sections. The stacks such as above described are then secured in their clamp or casing, or both, of which I have illustrated several forms as hereinafter described.

In one form of my invention (illustrated in Figs. 1-7 ,and' 10), the casing or clamp comprises, as shown in Fig. 4, a box-like part, clip or member 15 comprising a bottom or transverse portion 16 and side portions 18 extending vertically therefrom, the remaining opposite free edges of the surface 16 being provided with outwardly upturned ribs or edges 17 constituting reinforcing or stiffening means with the side portions 18. At the edges of the side portions 18 are lugs or tongues 19 for the purpose hereinafter described. This box-like member 15 is provided with inwardly-projecting lips 20 at opposite ends, which are sufliciently separated to provide a casing open at its opposite ends 21. The member 15 consists prefer- 'ably of sheet metal such as iron, and is of a form which may be very easily stamped out and shaped as illustrated in Fig. 4. In assembling the condenser stack within the part 15, the stack is preferably insulated therefrom by means of an insulating sheet 22 (Figs. 1 and 3), preferably of fish paper, separately illustrated in Fig. 7 which has reduced portions 23 at opposite ends providing notches 24 at the several corners thereof. The sheet 22 is assembled against the inner surface of the bottom 16 of the 'part 15 with its ends 23 projecting through the open ends 21 of 15 as illustrated in Figs. 1 and 2 and with its notches 24 co operating with the inwardly-directed lips 20 of the member 15, whereby the insulating plate 22 is locked within the member 15. The insulating parts 25, illustrated in Fig. 6, which may consist likewise of some cheap insulating material such as fish paper, are next assembled vertically against the inner walls 18 of the member 15. Each insulating strip 25 has at its opposite ends offset portions 26 providing intermediate portions 27 at right angles to the general plane of the part 25. The intermediate .portions of the parts 25 engage the inner sides of the casing portions 18 (Fig. 4), the parts 27 engage the parts 20 of the casing member 15, and the ends 26 project beyond the casing proper as illustrated in Figs. 1 and 2. The parts 27, co-operating with the parts 20, lock the insulating members 25 within the casing against movement. I After these insulating parts 22 and 25 are assembled within the casing, the stack is then positioned. Upon the stack is placed a secsteel separately shown in Fig. 5, is then secured in position on top of the part 15 as illustrated in Figs. 1 and 3. This is done preferably by passing the tongues 19 at one side of member 15 through slots or holes along one cdge of the member 29 and then bending the tongues 19 over to lock one side of the plate 29 in position as illustrated in Figs. 1 and 3, and after this is done the opposite side of spring member 29 is presed .down flat, placing the same under spring tension and secured in position by inserting the opposite pair of tongues 19 of member 15 through the opposite pair of'slots 30 in member 29 and bending them over, securing plate 29 in clamping relation.

' Inasmuch as the total thickness of the stack and fish paper insulators 22 and 28 exceed the height of the side portions 18 of member 15, the member 29 when locked in; position under tension exerts a resilient spring pressure upon the active area of the stack, keepingthe stack under constant pressure irrespective of temperature changes therein and thus making the losses lower, reducing brushing, and maintaining the capacity constant. The spring plate 29 is. placed parallel with the sheets composing the stack and the complete clamp or casing comprising combined parts 15 and 29 constitutes a rigid connection between the flat portions en- 1 gaging opposite sides of the stack, the parts 18' providing a rigid connection at right angles to said flat parts. The angularportion 31 extending from the plate 29 is for the purpose of securing the condenser to any suitable support.

The portions of the insulators 22, 25 and 28 projecting beyond opposite ends of the casing or clamp 15 provide open-ended boxlike insulating structures 32 (Figs. 2 and 10) at opposite ends of the casing beyond the stack through which pass or project the stranded leads 9a,-10a, 11a and 12. As

' shown more clearly in Figs. 1, 2 and 3, these leads are arranged or connected to the several parts of the condenser stack in spacedapart and staggered relation, whereby they are more thoroughly insulated from each other. Furthermore, as shown in Fi 3; these leads project from the stack at such points that they are separated from each other 'by the fish paper or mica separators 13.

The leads are also protected from contact with'the metal casing by the box-like openended-projecting portions 32 of insulating material. The box-like portions -32, after the condenser is assembled, are filled with some fusible insulating material such as a mixture of molten beeswax and rosin or with molten sulfur which is hard at normal temperatures. This forms upon solidification an embedment for the several leads 9a, 100, 11

and 12, which grips them and maintains them,

rigidly in position and prevents their bending around their points of connection to the foil terminals. The leads therefore are very rigidly and securely positioned on the condenser, first by sold'ering their fanned-out ends to the foil terminals in the manner described above, and secondly by embedding the inner portions thereof in said solid, hard, insulating material which prevents all movement thereof adjacent the inner ends of the leads, the outer ends of the leads, of course, being free to be bent for attachment to diflerent points.

In the forms of the condenser herein illustion; that is, a series: antenna condenser, the

condenser may be connected in the radio circuit to give difl'erent capacities. For this purpose, the lead 9a is the common lead of the system, while the leads 10a, 11a and 12 may be each connected up as desired to form a condenser circuit with the lead 9a. In the specific embodiment of the invention here illustrated, with. the leads 9a and 10a connected, gives a capacity of .0004 mid; with the leads 9a and 11/; connected, gives a capacity of .0002 mfd.; with'the'leads 9a and 12 connected, gives a capacity of .0003 mid.

The condenser stack is thoroughl insulated from the casing by said insu ating plates 22, 25 and 28 arranged to form terminal insulators 32, filled with suitable insulating material such as those specified above. By providing some conductive foils of increased tensile strength over the others, such foil terminals at opposite ends of the condenser are" made strong so that the stranded terminal leads may be securely soldered thereto without danger of tearing the foil tabs. Furthermore, in this construction there is very little danger of tearing the leads off for the reasons above mentioned. The plate 29 is of spring steel, and all the parts are easily formed vand easily assembled, reducing the cost of the condenser to a minimum. j

The embedments or fillers within the boxlike portions tion and coating of the terminal leads, looking them in position, preventing a side motion-,gwhich might in time break them.

IIiFigs. 12 to 18, 1 have illustrated another embodiment oftheinvention. The stack S 32 providea thorough insulaing sections connected in series and having separators interposed between the sections, and extending be ond the connections. It is to be understo however, that the condenser stack of the present invention may comprise any number of sections, one or more, either of the double type or single type herein described or combinations thereof to bring the leads out at opposite ends of the stack.

The stack S, when assembled and processed as above described, is maintained under pressure in a clamp C. This clamp comprises two metal parts or clips 35 and 36 (Fig. 17 which, when not assembled around the stack, have concavo-convex spring parts 37 and 38 adapted to engage the opposite sides of the stack and maintain a spring pressure over substantially the entire active area of the stack, holding the sheets thereof in intimate contact. The art 36 comprises rigid lateral portions 39 w ich are cut away at 40, forming tongues 41 at each side. In like manner, art 35 is provided withtongues 42. When t e stack S is to be assembled within the clamp C, insulating cover slips (not illustrated) may be placed upon opposite sides of the stack, if so desired, and then insulating sheets, spacers or blocks 43 (Fi s. 13 and 15) which cover the active area of t e stack and are of sufiicient thickness to prevent losses in the clamp and to insulate the stack from the clam The sheets 43 may be of mica if so desire Outside of the sheets 43 are then located insulating sheets or spacers 44 (Figs. 12, 14 and 15) which project beyond the ends of the stack and beyond the clamp. These likewise ma be of mica. The clamping parts 35 and 36 (Fig. 17) with the convex portions 37 and 38 engaging the opposite sides of the stack are placed under pressure as by a vise, of the order of 600 pounds. This flattens out the portions 37 and'38 against the stack. The tongues 41, while the pressure is applied, are then bent over the part 35, at opposite sides of each of tongues 42, the latter fitting over each of the portions 39. The material, preferably of vanadium steel, of which the clamp C (35 and 36) is composed should be of suflicient rigidity to hold the clamp parts locked, and to maintain a spring pressure exerted over the active area of the stack, and to form a rigid connection between the sprin parts 37 and 38 which are arranged paral el with the opposite sides of the stack and parallel with the sheets composing the stack.

After the clamp G has been applied, the clamp and the stack are treated in a paraflin bath at a temperature of about 100 C. for a period of about fifteen minutes, or until bubbling ceases, either with or without the application of vacuum, as desired or required, in order to remove air from the stack.

Although any number of leads (two or more) may be used, in the present embodiment of the invention, I have here illustrated a type of condenser which isespecially adapted or use as a series antenna condenser. For this purpose, the condenser is provided with four leads (Fig. 12), which are taken ofli' the condenser stack at various oints according to the desired capacities. Sew trally of the foil tab or free terminal 45 (Fig. 15) of an outermost stack section is soldered a suitable lead 46. A similar lead 47 is soldered to the fifth section at the opposite end of the stack at a point near one end of the connection (see Figs. 12, 13 and 15). A lead 48 is soldered to the seventh section at a point centrally of the connection and on the sameend as lead 46. A lead 49 is soldered to the outermost section at the opposite side of the stack and on the same end as the leads 47 and 48 at a point on the free terminal remote from the point of attachment of lead 47.

In the embodiments of the invention illustrated, the several leads referred to above consist preferably of stranded wire having ends flared out and soldered to the respective sectional connections or terminals as above described.

In order to protect the stack S, to provide a neat condenser, and to maintain the leads separate fro n'each other and invposition, I have provided encasing means E, the parts of which are illustrated in Fig. 16. This casing E comprises a metal box-like member 50, having a bottom and sides but open at the ends and top, the bottom and sides at the ends having inwardly directed flanges or lips 51. The longitudinal upper edges 52 of the sides are V-shaped, forming outwardly facing grooves adapted to interlock with a cover 53 having a V-shaped rim 54 adapted to fit around member and interlock with grooves 52 as illustrated in Figs. 13 and 14.

The cover 53 also has flanges 55 at opposite ends and adapted to fit over the flanges 51 and form therewith end frames for the easing for a purpose hereinafter described.

In assembling the stack S and clamp C (Fig. 17 in the casing E, (Fig. 16) insulating bushings 56 are threaded over the several leads (Figs. 12 and 15). Each of these bushin is provided with a flange 57 which is locate at the inner end of each lead. The bushings are preferably of bakelite, mica or other insulating material. The ends of the casing E are closed by insulating sheets or end pieces 58 and 59, preferably of mica.

These sheets are provided with openings 60 corresponding in number to the number of leads and into which are inserted the bushings 56 as illustrated, with flanges 57 up against their inner sides. The insulating end plates 58 and 59 are fitted back of flanges 51 (Fig. 16) which prevent them from falling out. Said plates 58 and 59 are also provided with notches 61 upon opposite sides near the top and adapted to receive the V-shaped edges 52 to lock them in position. After the bushings 56 with their leads are threaded through the end plates 58 and 59, the condenser and knots 62 may be laced in the leads to prevent them from eing pulled out through the bushings and thus preventing rupturing of their connection to the foil terminals or connections. When the embedment W within the-casing E is of a hard insulating material such as. sulfur, which sufliciently grips the leads, the knots may be omitted. It is 3 above described, the sides of member may beheld-against the edges of plates 58 and 59,

also preferable to so direct the leads through the bushings that bends or slack are provided in them, as illustrated in Fig. 15. Where several leads pass through the casing at one end as in this embodiment of Figs. 12-18, overlapping or crossing of the leads should be prevented. In order to prevent the lead 46 from short-circuiting the section connections at the end of the stack to which it is attached, I insert an insulating plate or shield 63, preferably of mica, transversely of the stack between-barrier 44 and lead 46 (Fig. 15). The .plate 63 has a notch 64 (Fig. 14) therein in which the lead 46 is located and whereby it is held away from its section connection.

After the parts have been assembled as iffound necessary, by any suitable means, as by a' vise, and the clamp and stack are embedded in an insulating material W, such as paraffin, a halogen wax or sulfur. This is done by pouring into the casing E molten sulfur or paraffin or other insulating material and allowing it to solidify. Thecover .53 is then snappe over member 1 50 withlthe parts 52 and 54 interlocking,

there .being sufficient spring in the sides of member 50' to hold the. arts securely together, forming a tight t, whereupon the condenser may be removed from the vise. If desired, a plate 65 (Figs. 12-16) may be spot welded, or otherwise secured to the bottom of member 50, the plate 65 being provided with apertured lugs or mounting feet whereby the condenser may be secured to a suitable support.

The casing of Figs. 12-16 for the clamped stacks of Figs. 1-3 and 12-15 is characterized by being capable of being manufactured at low cost. The several leads are mounted on insulating end pieces which insulate them from each other and from the casing, and which at the same time form closures for the casing. The bushings 56 with the insulating ends pieces 58 and 59 prevent creepage both inside and outside of the casing, while the.

embedment or filler W forms a solid gripping hard mass around the leads within the casthe parts of the casing together and can be easily snapped into position.

Before the molten sulfur is poured into the casing E. it should be heated to a temperature ofabout 120 C. and then removed from the burner. Into this molten sulfur,

.which is now more or less liquid, should be stirred powdered sulfur, preferably .flowers of sulfur in sufiicient amounts until adistinct color change occurs and the sulfur has a mushy consistency. The object of the above process is to produce a form of liquid sulfur which thereafter will cool into a solid permanent form, i. e., the rhombic, without rst passing through an intermediate unstable solid form, i. e., the monoclinic, thereby preventing internal stresses, strains and.

cracking which occurs when the sulfur first passes into the monoclinic state and finall' to the rhombic state. The sulfur in this process with the powdered sulfur mixed therein remains upon cooling for some minutes as a fairly viscous liquid at a temperature of about 110 C. The mushy sulfur as above described is then poured into the casing filling the same. After the casing has been filled, and for a short time thereafter,

the sulfur is in a fairly soft state. The sulfur is then trimmed flush with the top of the casing by means of a knife. After thesulfur has thoroughly set, possibly after three hours or more, the condenser is tested and the cover is then snapped in position. The sulfur when treated as above described is found very fine, not only as a filler or embedment as herein described, but also for use as a dielectric in condensers.

By having several thicknesses of mica insulation of Figs. 12-15 (the parts 43 and 44) between the stack and metal clamp, there is provided a minimum capacity between opposite sides of the stack via the stack insulation and clamp and also means for thoroughly insulating the stack from the clamp. The mica end pieces 58, 5.9 (Fig. 16) constituting the insulating parts of the casing, with the I pacity is needed. In such cases, the capacity between the opposite sides of the stack, via the metal clamp, is reduced to a minimum, in

order to prevent any appfeniable current 7 from flowingthrough this path' causing losses. By minimizing the capacity between the opposite sides of. the clamp, via the clamp, there will be less danger of having the capacity of the finished condenser exceed the required tolerance limits. The clamp C, via the plates 43 (Figs. 1215), maintains the sheets of the stack in intimate contact under high spring pressure. The clamp Fig. 17) and easing (Fig; 16) can also be manufactured and assembled at low cost.- The insulating arrangements are also cheap and efficient.

Sulfur is especially adapted for an insulating filler or-dielectric. because it is very rigid and hard when it solidifies, gripping the leads and maintaining them in position. Up to a temperature of 100 C., it is not subject to cool flow. It has a Very low specific heat, allowing the condenser to rapidly rise to its ultimate maximum temperature. In case of a breakdown of the sulfur due to high voltages, it reheals without decomposition.

Referring to Figs. 19 and 20, I have illustrated form of condenser which differs from the construction of Figs. 12-18 in having two loads 10 and 11 instead of four, one projecting from each end. The stack S employed in the construction of Figs. 19 and 20 may be of the type illustrated diagrammatically in Fig. 8, providing a series stack in which leads may be brought out at opposite ends and insulated from each other and the casing E (Fig. 16) by means of the mica end pieces 58 and 59 and bushings 56 such as illustrated in Figs. 12 to 18. The construction of clamp C and casingE of Figs. 19-20 are identical'with those of Figs. 12 to 18.

It is to be understood that the invention is not limited to the embodiments and features specifically shown and described herein, but that such embodiments and features are subject to changes and modifications without any departure from the spirit ofthe invention.

' I claim 1. In an electrical condenser, a stack comprising alternate sheets of foil and dielectric, a clamp surrounding said stack, exerting pressure thereon and open at its opposite ends, insulating sheets interposed between said stack and clamp and pro ecting at opposite ends beyond the ends of the clamp providing box-like structures of insulating material at opposite ends, and terminal leads from said condenser extending through said boxlike structures.

2. In an electrical condenser, a stack comprising alternate sheets of foil and dielectric, a metal clamp for said stack compressing the same and open at opposite ends, insulating sheets interposed between the clamp and staclnlocked in position by said clamp, and extending through the clamp beyond the ends thereof. providing box-like structures at opposite ends, leads from the stack extending between said stack and clamp projecting beyond the opposite open ends of said clamp and providing box-like structures of insulating material at opposite ends, means being provided on the clamp for securing the stack and insulating sheetstherein, flexible leads soldered to the foil terminals of said condenser and extending through said box-like structures, and an embedment of fusible solid insulating material within said box-like structures, sealing in said leads and preventing movement thereof..

4. Inan electrical condenser, a stack comprising alternate sheets of foil and dielectric and having a foil terminal, a flexible lead having av flared unstranded portion soldered to said foil terminal at a plurality of points, a casing having an open-ended extension through which said lead extends and a filler of solid insulating material surrounding said lead within said extension and embedding said lead and holding it in position.

5. In an electrical condenser, a stack comprising sections connected in series, separators between sections, leads extending from certain of said sections whereby a combinatron of capacities may be obtained, a casing enclosing said stack and having opemended portions projecting beyond the stack through which said leads extend, said leads being arranged in said openended portions in spacedapart relation with reference to planes at right angles to each other and separated by said sectional separators, and a solid embedment of insulating material surrounding said leads within said open-ended portions of the condenser casing.

'6. In an electrical condenser, a stack eomprising alternate sheets-of foil and dielectric, metal clamping means therefor, sheets of insulating -material interposed between said clamping means and opposite sides of said stack and projecting beyond'an end of the stack, a flexible lead connected to said end of the stack and extending between said insulating sheets and a solid fusible insulating -material supporting said lead between said projecting sheets.

. In an electrical condenser, a stack havsheets interposed between said clamp and opposite sides of said stack and projecting beyond the stack at opposite ends, a metal casing a metal clamp therearound, insulating I ing enclosin said stack and clamp and com; prising insu ating end pieces retained in position by said insulating sheets and leads connected to opposite ends of the stack and ex 5 tending through said insulating end pieces between said insulating sheets.

8. In an electrical condenser, a stack having leads connected thereto at opposite ends,

a metal casing enclosing said stack and havm ing insulating walls at opposite ends and insulating bushings on. said walls through which said leads and said bushings extend.

9. In an electrical condenser, a stack having a clamp there around, a metal casing having insulating walls at opposite ends thereof,

leads connected to the opposite ends of said stack and extending through said insulating walls and a filler of solid fusible insulating material within said casing and surrounding go said stack and leads.

10. In an electrical condenser, a stack ineluding series sections, ametal casing for said stack and including an insulating end, a flexible lead attached to one end of said stack and extending through said insulating end and a transversely arranged sheet of insulation for holding said lead away from the sectional connections.

11. In an electrical condenser, a stack havrial within the casing around the stack and leads, and a cover having interlocking engagement with the casing to hold the parts together. 1

13. In an electrical condenser, the combination with a stack of dielectric sheets and foil armatures, of a sheet metal clamp for said stack, a sheet metal casing enclosing .four sides of said clamped stack. but. open at its ends adjacent the stack ends; insulatingplates closing said casing ends; leads extending from the stack-ends out thru said insulating plates; and a solid insulating filler within said casing around the clamped stack and the parts of theleads inside the casing. 7 14. In an electrical condenser, the combination with a stack of dielectric sheets and foil armatures, of a sheet metal stack-clamp comprising two adjacent portions each interlocking with the other thereby securing the clamp in clamping relation to the stack, and insulated from at least one terminal of the stack; and a sheetmetal casing enclosing said clamped stack and also insulated from at least one terminal of the stack.

15. A condenser comprising condenser elements, and a band clamp embracing the con denser, said clamp having a pair of transverse bends therein adjacent each end, and with portions adjacent the outer bend capable of flexing when the clamp is tightened, to enable the clamp to serve for condensers of difierent thicknesses.

16. A condenser comprising a stack containing one or more sheets of conductive material separated by insulation,;a clam embracing said stack, the clamp being 0 stifl, strong, bendable material, and extending over one face of the stack, the clamp being bent across both sides of the stack with its ends turned down against the opposite face, the ends of the clamp being separated, a plate on said opposite face with its opposite edges beneath the separated ends of the clamp and held thereby firmly against said opposite face of the stack, said clamp and plate forming a casing for the stack open at both ends, through which the two extremities of the stack appear, part of the conductive sheets being exposed at one end of the condenser, and part at the other end' to enable the condenser to be connected to an electric circuit.

17.-An electric condenser comprising dielectric and armature members, means under pressure around said members, a sheet metal casing having an open side through which said members and means are insertable into the casing, terminal means for connecting said members with an external circuit and adapted to temporarily support said'members and pressure means within and spaced from the metal casing, a solid plastic insulatingembedment surrounding and supporting said pressure means and members'wit in and in spaced relation to the casing, insulating means closing the casing against egress of embedment during pouring of the embedment.

18. An electric condenser comprising dielectric and armature members, means under pressure around said members, a metal casing enclosing said members and pressure means, aterminal projecting from said casing, a flanged bushing surrounding said terminal with the flanged portion within the casing and an unflanged portion of the bushing extending through the casin to the outside and a plastic insulating em dment cooperating with the inside flanged portion to hold said bushing in position, the casing wall around said bushing being a sheet of insulating material.

19. An electric condenser comprising dielectric and armature members, means under pressure around said members, a metal casing enclosing said members, terminals projecting from opposite sides of saidymembers and out of the casing, said casing being of sheet metal open on the longitudinal side thereof for insertion of the members, insulating material in sheet form closing the casing around the projecting terminals to prevent egress of plastic insulating embedment material, and such material enclosing said members and spacing the same from the casing walls on at least three sides.

20. An electric condenser comprising dielectric and armature members, a sheet metal casing having one side open, flanges extending inwardly on the open side, a sheet of insulating material closing said open side and .tween the casing and side members, terminals projecting out of said casing, the portion of the closin means for the longitudinal side being yie dably sprung in place.

22. An electric condenser comprising dielectric and armature members, a sheet metal channel-shaped casin means for closing the ends and a longitudinal side of the casing, plastic insulating embedment material between the casing and side members, terminals projecting out of said casing, the base of the casing being provided with a thicken.- ing reinforcing and supporting portion having laterally supporting ears.

WILLIAM H. BRIESS. 

